It is the common practice to carry live bait and live caught fish in tanks which are mounted or built into the boat. However, live bait and fish cannot be kept alive in stale uncirculated water for any extended period of time because the water will become deoxygenated and/or fouled causing the bait or fish to die. Therefore, in order to maintain maximum life of the bait and the fish, live well support systems have been developed to both recirculate and oxygenate water in the tank. In addition to the tank position in the boat, centrifugal pumps are provided for pumping water from outside of the boat into the tank and the tank has an overflow allowing water to drain out of the tank. Typically, the pumping means includes a through-transom fitting mounted in the boat transom below the normal water line and the pump is mounted inside the boat on a fitting with a hose leading from the pump to the tank. The fitting is generally mounted above the planing surface so that there is no drag and it draws fresh water from outside the hull.
Additionally, many boats contain bilge pumps for the purpose of pumping accumulated water from the boat. Typically, such a bilge pump is mounted at or near the lowest point of the transom or hull of the inside of the boat. A through-hull or -transom fitting is mounted in the hull or transom below the water line and a hose leads from the pump to the fitting. When the pump is activated, water is drawn from the bilge through the pump and forced out of the boat through the hose and fitting.
The pumps generally used in the above two systems are centrifugal pumps having a circular chamber and a rotary impeller positioned therein. With the live well pumps, if the supply of water is not adequate, such as when the water intake fitting rises above the water level outside of the boat when the boat is planing or when rough water causes the fitting to be exposed to the air, the pump becomes air locked and is unable to continue pumping water. The pump remains air locked and the impeller is unable to pump water so long as the impeller is being driven because it just keeps recirculating the same air. It is believed this results in a donut shaped air bubble that encompasses the impeller blades.
An air lock is most typically cleared by turning the pump off thus releasing the back pressure of the air and allowing the water in the pump outlet hose to fall back through the pump, forcing the trapped air out of the chamber. The pump is then restarted permitting the impeller blades to return to normal pumping of the water. Alternatively, if the live well fitting is mounted in the boat transom, the boat may be driven rapidly in reverse forcing water into the fitting and the pump chamber, clearing the air lock. Both of these methods are cumbersome and impractical because they first require the boat operator to discover that the pump has been air locked and then to take one of the above actions to correct the problem.
One pump that has addressed this air lock problem is disclosed in pending U.S. Patent Application Ser. No. 561,587 filed on Dec. 14, 1983, now abandoned. This pump is of the type in which the chamber is oriented in a vertical direction and having an inlet opening at the bottom thereof with an outlet port mounted upwardly above the impeller. This pump has successfully corrected the problem or air lock by providing a plurality of spaced vanes circumferentially mounted around the impeller blades. These blades cut into the air pocket as the impeller blades are rotated causing turbulence that breaks up the air pocket. However, for many uses the upwardly extending housing required for this type of centrifugal pump is undesirable because of the space it occupies. Therefore, there has been a need for a low profile pump, i.e., one in which the cylindrical chamber is mounted on the horizontal rather than on the vertical. This orientation of the chamber presents entirely new problems that cannot be solved by a plurality of baffles or blades mounted circumferentially about the impeller blades and, therefore, to my knowledge no low profile centrifugal pump with a chamber arranged on the horizontal has existed to date.